Coiled spring well instrument positioner

ABSTRACT

An apparatus for positioning a well instrument in the proper position in a bore hole for performing a desired well operation. Each end of a coiled spring is attached to the body of the well instrument. The coiled spring projects outward at right angles to the body of the well instrument and contacts the wall of the bore hole insuring that the well instrument is in the proper position for performing the desired well operation. When used with a sidewall sampler the coiled spring absorbs recoil energy when the sampling guns are fired. When the well instrument is being moved through restrictions in the bore hole, the coiled spring will deflect along the side of the well instrument allowing the well instrument to easily pass through the restriction.

United States Patent [191 Wolk [111 3,842,918 1 Oct. 22, 1974 1 1 COILED SPRING WELL INSTRUMENT POSITIONER [75] Inventor:

[52] US. Cl. 175/4, 175/451 [51] Int. Cl E2lb 49/04 [58] Field 01' Search 175/2, 4, 4.51, 4.52, 4.53;

[56] References Cited UNITED STATES PATENTS 2,787,328 4/1957 Atkinson 166/173 2,915,089 12/1959 Horsting 166/241 X 3,213,943 10/1965 Solum 166/173 3,269,467 8/1966 Bell 175/451 3,366,188 H1968 Hicks 175/452 X 3,648,612 3/1972 Grayson lO2/2l.8 X 3,688,849 9/1912 Briggs 175/452 3,707,195 12/1972 Lanmon ..l75/4.52

Primary Examiner-David H. Brown Attorney, Agent, or Firm-Eddie E. Scott; John N. Hazelwood 5 7 ABSTRACT An apparatus for positioning a well instrument in the proper position in a bore hole for performing a desired well operation. Each end of a coiled spring is attached to the body of the well instrument. The coiled spring projects outward at right angles to the body of the well instrument and contacts the wall of the bore hole insuring that the well instrument is in the proper position for performing the desired well operation. When used with a sidewall sampler the coiled spring absorbs recoil energy when the sampling guns are fired. When the well instrument is being moved through restrictions in the bore hole, the coiled spring will deflect along the side of the well instrument allowing the well instrument to easily pass through the restriction.

5 Claims, 10 Drawing Figures PAIEN [ED 2 SHEUIU3 CONTROL EQUIPMENT FIG.

PRIOR ART FIG.

PRIOR ART PRIOR ART PAIENIEU 3.842.918

2; 33 34 FIG. 8 9 33 PRIOR ART FIG. 9

PRIOR ART COILED SPRING WELL INSTRUMENT POSITIONER BACKGROUND OF THE INVENTION The present invention relates to a positioning apparatus for well instruments and more particularly to an apparatus for positioning a well instrument in the proper position for performing a desired well operation.

Well instruments must be somewhat smaller in diameter than the well bore they are to be used in. This allows the well instrument to pass freely through the well bore and through any restrictions in the well bore. Once the well instrument reaches the proper depth it is desirable for the well instrument to be placed in a preferred position with regard to the wall of the well bore. Bow springs and movable arms have previously been used to maintain the well instrument in the desired position for performing the well operation. The present invention provides a novel apparatus for maintaining the well instrument in the desired position for performing a well operation.

The exploration and production of oil and gas and other natural substances found in formations or strata of earth or rock below the surface of the earth is generally achieved by means of a borehole drilled into the formations Although various techniques are available for gaining information with respect to the location and character of formations underlying previously undrilled areas of the surface, such information is only approximate. Thus, other techniques are often utilized during and after drilling operations to obtain samples of the material being penetrated. One well known technique for obtaining these samples includes cutting a "core" of the rock or earth by means of a tubular-shaped drill bit affixed at the outer end of a drill string. This method is time consuming and expensive since each time a core is to be taken and raised to the surface the entire drill string must first be removed from the borehole. Thus, cores are generally taken only at limited intervals throughout the drilling operations. Retractable core barrels that can be returned to the surface through the drill string are also known; however, such core barrels require a substantial amount of specialized equipment including special elements in the drill string.

A sampling technique that may be performed at substantially less cost involves the use ofa wireline tool for selectively obtaining samples from the wall of the borehole at any desired level. This tool, commonly known as a sidewall sampler." includes an elongated body containing a plurality of apertures along its length which function in the manner of short gun barrels with each such barrel having an explosive charge and a sample container projectile adapted to be laterally discharged thereby into the wall of the borehole. Electrical circuitry for achieving ignition of the charges from a control point at the surface is generally included. Further, since the cores taken by the sample container projectiles are intended to be recovered, the projectiles are generally coupled to the sidewall sampler body by means of one or more small cables. Thus, when the sidewall sampler body is withdrawn from the borehole these cables permit the sample container projectiles containing the cores to by puiletl uut of the borehole wall and carried to the surface along with the sidewall sampler body.

In operation the sidewall sampler may be lowered by means of conventional cabling and hoist equipment to that section of the borehole adjacent the formations sought to be sampled. Thereafter, one or more of the guns" may be tired to discharge corresponding sample container projectiles laterally into the adjacent formations. When the sampler is drawn up the borehole. the aforementioned small cables which remain attached to both the sidewall sampler body and the embedded sample container projectiles serve to drag the projectiles out of the formation as the sampler is drawn up the borehole.

Notwithstanding the advantages of selectivity and speed of sampling afforded by the sidewall sampler, certain problems have been encountered with use of the sidewall sampler in inclined boreholes. Boreholes that deviate from a vertical position generally have an oblong cross section with the largest axis of the borehole oriented in the relative vertical direction. During the sampling operation, the sidewall sampler body rests against the bottom of the deviated borehole and should the sampling guns be facing the top of the borehole, the sample container projectiles must cross the borehole before reaching the formation to be sampled. This may result in the snapping of the cables connecting the sample container projectiles to the sidewall sampler body and loss of the desired sample. Unfortunately, many of the sidewall samplers are constructed in such a manner that the center of gravity of the instrument is located at a position that results in the sidewall sampling apparatus being oriented in the boreholes in the undesirable position of having the sampling guns facing toward the top of the borehole. Prior art methods of combating this problem have been concerned with centralizing the sidewall sampling apparatus in order to insure that the apparatus will be properly oriented in the borehole. The present invention attacks the problem in a substantially different manner by providing means for turning the sidewall sampling apparatus over so that the sampling guns are facing in a relatively downward direction.

When the sidewall sampler apparatus is being moved through the borehole, it will be required to pass through restrictions and a rigid projecting structure would be unsuitable. For example, the sidewall sampler may be required to pass through a blow-out preventer or other well restriction when the sidewall sampler is being lowered or withdrawn from a well bore. A rigid projecting structure would present the sampler from moving past the restriction.

DESCRIPTION OF PRIOR ART In US. Pat. No. 3,272,268 to A. J. Tricon et al. pa tented Sept. 13, 1966.21 sidewall sampling apparatus is shown. This sidewall sampling apparatus includes an elongated shaft containing a plurality of apertures which function in the manner of short gun barrels. An explosive charge is positioned in each of such gun barrels and a projectile adapted to be laterally discharged thereby into the wall of the borehole is also positioned in the gun barrel. When the explosive charges are detonated, the projectiles are fired into the formations adjacent the apparatus. The projectiles are connected to the apparatus by cables. When the sampler is drawn up the borehole, the aforementioned cables which remain attached to both the sampler and the embedded projectile serve to drag the projectile out of the formation thereby carrying the desired sample to the surface.

In US. Pat. No. 2,587,244 to W. G. Sweetman, patented Feb. 26, 1952 an apparatus for cutting pipes within a well is shown. One embodiment of the apparatus utilizes bow spring members arranged on the outside of the apparatus housing that bear against the side of the wall of the casing to position the apparatus against the opposite wall of the casing.

SUMMARY OF THE INVENTION The present invention provides a well instrument positioner that will effectively position a well instrument in the proper position for performing the desired well operation. The well instrument includes a body portion adapted to be moved through a borehole by a cable. A coiled spring is attached to the body of the well instrument for positioning the well instrument in the proper position for performing the desired well operation. Each end of the coiled spring is attached to the body of the well instrument with the body of the coiled spring projecting outward at right angles to the body of the well instrument. The coiled spring contacts the wall of the borehole and maintains the well instrument in the proper position for performing the desired well operation. The coiled spring will deflect to the side of the well instrument to allow the well instrument to pass through restrictions in the borehole. When used with a sidewall sampler the coiled spring absorbs recoil energy when the sampling guns are fired. The above and other features and advantages of the present invention will become apparent from consideration of the following detailed description of the invention when taken in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a pictorial view partly in cross section of a prior art sidewall sampler positioned in a borehole.

FIG. 2 is a view of one of the coring projectiles of the sampler shown in FIG. I after the projectile has been fired into the formations surrounding the borehole.

FIG. 3 is an end view of a prior art sidewall sampler positioned in a borehole.

FIG. 4 is a side view of a sidewall sampler including the coiled spring positioner of the present invention.

FIG. 5 is an enlarged view ofa portion of the sidewall sampler shown in FIG. 4.

FIG. 6 is an end view of the sidewall sampler shown in FIG. 4 positioned in a borehole.

FIG. 7 is an enlarged view ofa portion of the sidewall sampler shown in FIG. 4 positioned in a borehole.

FIG. 8 is a side view of a prior art sidewall sampler with a bow spring positioner.

FIG. 9 is an end view ofthe prior art sidewall sampler shown in FIG. 8 positioned in a borehole.

FIG. 10 is an end view of a sidewall sampler constructed in accordance with the present invention positioned in a boreholev DETAILED DESCRIPTION OF THE INVENTION Referring now to FIG. I, a sidewall sampler l of the prior art is shown. FIG. I shows atypical borehole 2 extending from the surface of the earth 3. The borehole 2 contains the prior art sidewall sampler l suspended therein b a cable 4 which is secured to the sidewall sampler I by means ofa cable head 5. The cable 4 may be of c nventional design to include one or more electrical conductors as desired. The cable 4 is connected to control equipment 6 located at the surface and is used to move the sidewall sampler I in and out of the borehole 2. The depth at which the sidewall sampler l is positioned in the borehole 2 may be determined by means of a conventional measuring wheel 7 from which the cable 4 is suspended and over which the cable 4 is drawn.

As shown, the sidewall sampler 1 includes an elongated body 8 having a plurality of projectiles 9 arranged in a manner to be discharged laterally into the wall of the borehole 2 as will hereinafter be explained in greater detail. As illustrated in FIGS. 1 and 2, each projectile 9 is also connected to the body 8 by means of one or more cables I0 or other type of flexible linking means of some suitable design.

Referring to FIG. 2, there is depicted therein a section of the borehole 2 and body 8 hereinbefore mentioned wherein the projectile 9 has been discharged into the wall of borehole 2 in a manner to take a sample of the adjacent earth 3. As shown in FIGS. 1 and 2 the projectile 9 is provided with enlarged cutting edge II to cut a core hole 12 of a diameter larger than that of the body of the projectile 9 to prevent the projectile 9 from becoming too tightly embedded in the more impacted formations of the earth 3. The attached cables 10 should be long enough to permit the projectile to penetrate the earth 3 at depths sufficient to pass beyond any drilling mud which may be deposited on the face of the wall of the borehole 2. When the body 8 is drawn out of the borehole 2, the cables I0 will serve to pull each projectile 9 out of its respective core hole 12 and to carry it upward in order that the cores contained in each projectile 9 may be recovered at the surface for testing and analysis. It is thus apparent that since boreholes such as that depicted in FIGS. 1 and 2 are ofa relatively small diameter, body 8 must of necessity be even smaller in diameter and consequently the gun barrel 13 of each gun must be at least somewhat shorter in length than the overall diameter of the body 8.

Referring now to FIG. 3, the sidewall sampler 1 of the prior art is shown positioned in a deviated or inclined borehole 14. The borehole 14 has an elongated cross section generally found in deviated boreholes. When the prior art sidewall sampler I is resting on the lower side 15 of the borehole 14, there is a considerable distance between the body 8 of the sampler l4 and upper side 16 of the borehole 14. It will, therefore, be appreciated that the sampling projectile 9 of the sampler I will be required to travel a substantial distance before reaching the upper side 16 of borehole l4 and that there is a considerable loss of kinetic energy before the sampling projectile 9 reaches the formation at the upper side 16 of the borehole 14. In addition, a risk exists that the attaching cable 10 will be broken because of the distance between the sampler l and the upper side I6 of the borehole 14. A broken cable would result in the loss of the sampling projectile 9 and failure to obtain the desired sample. The geometry and weight distribution of the sampler l is such that the sampler tends to rest on the lower side 15 of deviated boreholes with the projectiles 9 pointing toward the upper side of the borehole.

Referring now to FIG. 4. a sidewall sampler having a coiled spring positioning apparatus is shown. The side wall sampler is generally designated by the reference number 17. The sidewall sampler 17 includes an elongated body 18 having a plurality of projectiles l9 arranged in a manner to be discharged laterally into the wall of a borehole. A coiled spring is attached to the upper end of the body 18 and a coiled spring 21 is attached to the lower end of the body 18. The coiled springs 20 and 21 project outward substantially perpendicular to the body 18 of the sidewall sampler 17. The upper coiled spring 20 is shown in greater detail in FlG. 5. One end 22 of the coiled spring 20 fits within a hole 23 in a bracket 24 projecting from the body 18. The end of the wire 25 that makes up coiled spring 20 is affixed to the bracket 24. The other end 26 of the coiled spring 20 fits within a hole 27 in the bracket 24. The other end of the wire 28 that makes up the coiled spring 20 is affixed to the bracket 24.

Referring now to FIG. 6, the sidewall sampler 17 is shown positioned in an inclined or deviated borehole 29. The coiled springs 20 and 21 contact the wall of the borehole 29 and maintain the sidewall sampler 17 in a position wherein the sampling projectiles 19 are facing and proximate the wall of the borehole 29. If it becomes necessary for the sidewall sampler 17 to pass through a restriction in the borehole 29, the coiled springs 20 and 21 will deflect axially along the sides of the body 18 allowing the sidewall sampler 17 to pass through the restriction. As shown in HO. 7, the spring 20 has contacted a projection 30 extending from the wall of the borehole 29. The coiled spring 20 has been deflected toward the side of the body 18 and the sidewall sampler 17 can pass through the restriction created by the projection 30. Once the sampler 17 has passed through the restriction, the coiled spring 20 will spring back into its original position projecting substantially perpendicular from the body 18.

A mercury switch is positioned in the sidewall sampler 17 to provide an indication that the sampler is in a position for firing. The mercury switch may be of conventional design, for example, it could the type shown on page 282 of the Electronics and Neucleonics Dictionary, Cook and Markus, McGraw-Hill, 1960. The mer cury switch closes an electrical circuit that includes a signal means at the surface when the sidewall sampler 17 is in position for firing as shown in FIG. 6. The mercury switch remains open when the sampler is in other positions.

Referring now to FIG. 8, another prior art sidewall sampler 31 is shown. The sidewall sampler 31 includes a body 32 adapted to be transported through a borehole by a cable in the conventional manner. A multiplicity of sampling projectiles 33 are mounted on the body 32 and arranged in a manner to be discharged laterally into the formations surrounding the borehole (not shown). A bow spring 34 is mounted on the body 32 for positioning the sidewall sampler 32 in the proper position for firing. The sidewall sampler 31 is positioned in an inclined borehole 35 as shown in FIG. 9. The central axis 36 of the sampling projectiles 33 determine the line offire of the sampling projectiles 33. The angle a between the line of fire central axis 36 of the projectile 33 and line 37 (a horizontal line) should approach for optimum performance of the sidewall sampler. It will be appreciated that the distance a between the central axis 36 of the sampling projectile 33 and the point of contact of the bow spring 34 and the wall of the borehole 35 affects the firing angle 01". In the prior art sidewall sampler, the distance a is small and the firing angle is much less than the optimum 90 angle.

Referring now to FIG. 10, a sidewall sampler 38 is shown positioned in a borehole 39. The sidewall sampler 38 includes a body 40, sampling projectile 41 and coiled spring positioner 42. The distance a. between the central axis 43 of the sampling projectile 41 and the point of contact of the coiled spring positioner 42 and the wall of the borehole 39 is larger than the distance a of the prior art sidewall sampler 31. The angle a, between central axis 43 and line 44 (a horizontal line) is also greater than the angle a in the prior art sidewall sampler and approaches the optimum 90 angle. The coiled spring positioner 42 improves the performance of the sidewall sampler 38 by providing a better firing angle.

The embodiments of an invention in which an exclusive property or privilege is claimed are defined as follows:

1. An apparatus for performing a well operation in an earth borehole, comprising:

a body portion adapted to be transported through said borehole;

means for performing a well operation mounted in said body portion; and

a coiled spring affixed to said body portion, said coiled spring including a coiled spring body having a first end attached to said body portion and a second end portion attached to said body portion.

2. The apparatus of claim 1 wherein said coiled spring body projects substantially perpendicular to said body portion.

3. The apparatus of claim 2 including a second coiled spring with one end attached to said body portion and other end attached to said body portion.

4. An apparatus for sampling formations traversed by borehole, comprising:

a sampler body;

sampling projectile means positioned in said body for receiving a sample of the formation;

linking means connecting said body section and said sampling projectile means; and

a coiled spring with a first end affixed to said sampler body and a second end affixed to said sampler body with said coiled spring projecting substantially perpendicular to said sampler body.

5. The apparatus of claim 4 including a second coiled spring with a first end affixed to said sampler body and the second end affixed to said sampler body with said coiled spring extending substantially perpendicular to said sampler body.

l l l l k 

1. An apparatus for performing a well operation in an earth borehole, comprising: a body portion adapted to be transported through said borehole; means for performing a well operation mounted in said body portion; and a coiled spring affixed to said body portion, said coiled spring including a coiled spring body having a first end attached to said body portion and a second end portion attached to said body portion.
 2. The apparatus Of claim 1 wherein said coiled spring body projects substantially perpendicular to said body portion.
 3. The apparatus of claim 2 including a second coiled spring with one end attached to said body portion and other end attached to said body portion.
 4. An apparatus for sampling formations traversed by borehole, comprising: a sampler body; sampling projectile means positioned in said body for receiving a sample of the formation; linking means connecting said body section and said sampling projectile means; and a coiled spring with a first end affixed to said sampler body and a second end affixed to said sampler body with said coiled spring projecting substantially perpendicular to said sampler body.
 5. The apparatus of claim 4 including a second coiled spring with a first end affixed to said sampler body and the second end affixed to said sampler body with said coiled spring extending substantially perpendicular to said sampler body. 